Fault memory entries for the brake

In the diagnosis that took place when the reading lamp was replaced, there is an earlier fault memory entry from the brake booster. According to the manufacturer, this occurred on 28.4.2023. In the log available to me, this entry has no time stamp, so here again the manufacturer has the advantage of having more data.

Before my car was loaded onto the tow truck, the main battery was disconnected. When my fault memory was read out 3 days after my accident with the battery still disconnected, no faults were found around the brake booster. When the car was read out by the manufacturer 10 days after the accident and the battery was reconnected, entries then appear. According to the manufacturer, they have no relevance to my accident due to their time stamp.

In the chapter on the power of driver assistance systems, I describe that a fault may be masked. Is this the case here by switching off the vehicle and disconnecting the battery?

This error also coincides with my perception of the accident situation.

“The motor works against the brake”

What is there to know about the brake? Well, my electric car has a particularly long range because it works with energy recovery through the engine brake. This is known as recuperation. It’s now available everywhere, but was fairly new two years ago. This means that the driver steps on the brakes, but the car decides independently whether to use the engine brake instead of the disc and drum brakes based on the charge level. Again explicitly: As the driver, I have absolutely no influence on which brake is used by the vehicle. All this can be found here in the manual.

The following three features are described in the forums:

  1. Decreasing braking force shortly before standstill
  2. No smooth transition from recuperation to mechanical braking
  3. Slight onset of pushing of the electric motor below 5 km/h
  4. more likely to occur during braking with a new vehicle

I had already been to the garage about this fault before the accident, but the employee assessed it as satisfactory.

The following description is linked to this defect in the new software update:

(C46) Better transition between brake and engine at low speeds

“At low speeds (under 5 km/h) and light pressure on the brake, the electric motor kicks in at a certain point and “presses against the brake”. This is used to control the speed below 5 km/h without taking your foot off the brake. The first intervention of the electric motor is now more gentle.”
This error is described here in the wiki for software updates:

In the description of this feature improvement C46, it is explicitly mentioned that the car has a function that works against the brake. From this point on, I think it is negligent that in the event of an accident, the driver or the expert has no log and trace of the assistance systems available.

I requested a detailed description of the feature, in particular the calculation of the acceleration request for the counter-pressure to the brake and what this looked like at the time of the accident, from the manufacturer on 28.9.2023, but a reply is still pending.